[PATCH v3] nvmet-tcp: reject H2CData before ICReq

[Maurizio Lombardi]

On Tue Jan 27, 2026 at 3:37 PM CET, Maurizio Lombardi wrote:
>
> Nevermind, now I get what you mean: you can hit the bug if you send
> H2CData after ICReq but before the execution
> of the connect command.

I was able to reproduce the crash:

[25362.399746] BUG: kernel NULL pointer dereference, address: 000000000000000c
[25362.403368] #PF: supervisor read access in kernel mode
[25362.405451] #PF: error_code(0x0000) - not-present page

[...]

[25362.430592] Call Trace:
[25362.430945]  <TASK>
[25362.431250]  ? show_trace_log_lvl+0x1b0/0x2f0
[25362.431910]  ? show_trace_log_lvl+0x1b0/0x2f0
[25362.432507]  ? nvmet_tcp_done_recv_pdu+0x299/0x2f0 [nvmet_tcp]
[25362.433285]  ? __die_body.cold+0x8/0x12
[25362.433810]  ? page_fault_oops+0x148/0x160
[25362.434388]  ? exc_page_fault+0x73/0x160
[25362.434953]  ? asm_exc_page_fault+0x26/0x30
[25362.435573]  ? nvmet_tcp_build_pdu_iovec+0x4c/0xc0 [nvmet_tcp]
[25362.436357]  nvmet_tcp_done_recv_pdu+0x299/0x2f0 [nvmet_tcp]
[25362.437113]  nvmet_tcp_try_recv_pdu+0x1ef/0x2d0 [nvmet_tcp]
[25362.437856]  ? sched_balance_update_blocked_averages+0xdd/0x1a0
[25362.438672]  nvmet_tcp_io_work+0x70/0x8c0 [nvmet_tcp]

But it appears to have been already been fixed by commit 32b63acd78f577b332d976aa06b56e70d054cbba
(nvme-tcp: fix NULL pointer dereferences in nvmet_tcp_build_pdu_iovec)

dmesg output target-side:

[   54.436869] nvmet_tcp: queue 0: H2CData PDU received for invalid command state (ttag 43981)


Maurizio